Earlier this fall, my friends got together and placed friendly bets on when the first measurable snow would fall in East Middlebury. My bet was for October 28th, so I was excited earlier this week to read forecasts of accumulating snow on Thursday night. Then, yesterday morning, the snow was all but removed from the forecast!
So, what gives? Why do the forecasts seem to change so much? Are the meteorologists just guessing? Is there a forecaster bias towards dramatic (or comfortable) weather? Or, is there something else going on?
These days most weather forecasts are based on meteorologists' interpretations of a range of computer weather models that use current conditions, past weather records, and other factors to project possible future weather. These weather models have allowed for the existence of modern, relatively accurate weather forecasts, but they are not without their downsides. They have a tendency to change their 'minds' at the last minute, and are subject to bias and error. During times of changing weather, such as spring and fall, they are especially erratic. To make things worse, they have a very difficult time forecasting hurricanes, and it could be that Hurricane Rina is causing yet more confusion for the weather models. This, in turn, leads to a fluctuating forecast, and an unknown prospect for tomorrow morning.
The computer models often have difficulty forecasting which areas will get rain versus snow because just a couple of degrees can determine the precipitation type. For example, the heavy snowstorm of last March was initially predicted to be almost entirely rain. The temperature was a bit colder than expected, and instead of two inches of drenching rain on snow, we picked up two feet of wet snow. For this week, the question isn't the temperature as much as where the storm will go. Right now, the possible snowstorm seems to be slipping just south of us, leaving only light drizzle in Addison County. It is expected to be in the mid 20s tonight, so if the storm shifts north a bit we may experience some light snowfall. There is another storm that may move through the Northeast on Saturday, and the computer models can't quite figure this storm out either, but it looks like it may also miss our area.
October snow is not uncommon in Addison County, but is usually mostly restricted to the mountains. Salisbury averages 0.5 inches of snow in October, but in more cases than not does not pick up measurable snow in October at all. South Lincoln, in the Green Mountains, averages a bit over two inches of October snow, and averages one snowy October day each year.
This year, it looks like the peaks will pick up some October snow, but the lowlands may not see any accumulation. As of earlier this morning, Middlebury Snow Bowl was reporting snow, but here in East Middlebury there was very cold rain. But, outside my window right now, I see a few wet snowflakes flitting by. The weather is sure to surprise us, one way or another. There is still a chance that tomorrow morning we will wake up to a dusting of white.
Either way, we can be sure the snow will come, sooner or later.